Motor-switch.



O. B. DUNCAN.

MOTOR SWITCH.

APPLICATION mum IAYB, 1912.

1,106,639, Patented Aug. 11, 1914.

3 SHEETS-SHEET 1.

Dian/ca];

0. B. DUNCAN.

mo'ron swmcn.

APPLICATION FILED KAY 6, 1912.

1,106,639. Patented Aug. 11,191;

i SHEETS- HIST 2.

0. B. DUNCAN.

MOTOR SWITCH.

APPLICATION FILED IAYB, 1912.

1,1 06,639. Patented Aug. 11,1914,

3 SHEETS-SHEET 3. W 141 F UNITED STATICS PATENT OFFICE.

OTIS B. DUNCAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO GEORGE CUTTER COMPANY,OF

- SOUTH BEND, INDIANA, A CORPORATION OF INDIANA.

moron-swrrcn.

Specification of Letters Patent.

Patented Aug. 11, 1914.

Application filed May 6, 1912. Serial No. 695,466.

To all whom it may concern Be it known that I, OTIS B. DUNCAN, a citizenof the United States, residing at Chicago, in the county ofCook andState of Illinois, have invented a certain new and useful Improvement inMotor-Switches, of

;means for producing a quick automatic movement of the switch bladesfrom the starting to the running contacts as soon as the operatorconsiders that the motor has attained sufiicient speed to warrant thechange. This quick movement prevents arcing and burning of contacts. Itis common practice where motors are over five horse power, to bring outthe ends of the phase windings and provide means where-' by the windingsmay be star connected for starting the motor, and be then changed overso as to be delta connected after the motor has attained its normalspeed. It is my purpose, and one of the objects of the .invention. toaccomplish this by the aid of a switch having but four poles, all ofwhich are operable as a single piece.

Other objects'of the invention are to provide certain contributingdetails which will be hereinafter more specifically described andclaimed.

I obtain my objects by the mechanism illustrated in the accompanyingdrawings, in which Figure 1 is a perspective view of the inclosingcabinet and the operating lever on the top thereof. Fig. 2 is a frontelevation of the apparatus with the front door removed. Fig. 3 is a plansection of the apparatus. Figs. 4 and 5 are plan views of the operatinglevers, showing changed positions thereof. Fig. 6 is a top View of theoperating lever and associated parts. Fig. 7 is a sectional view on theline 7-7, Fig. 6. Fig, 8 is a fragmentary sectional view taken throughthe axis of the crank shaft.

Fig. 9 is a diagrammatic view showing star delta connections for athreephase inductlon motor.

Similar reference characters denote like parts in the several views.

In order to explain the invention in its most omplete, and one of itspreferred forms, I have selected the form best adapted for a three haseinduction motor started upon star connection and normally operated ondelta connection; although it will be understood that the quick throwmechanism is adapted for any type of motor which is started on one setof contacts and normally runs on another set. It will also be understoodthat the stationarycontacts may be wired up in other ways to suitdifferent requirements and conditions.

In the form shown in the accompanying drawings, the panel switch bladesand contacts are inclosed within a cabinet 1, having a front door 2which in the present instance is hinged at the top. The panel 3, ofslate or other suitable insulating material is fastened in anyappropriate manner to the inside of the back of the cabinet. I willfirst describe the quick throw mechanism and therefore, it will besufficient for the present to say that the switch blades are allconnected to and simultaneously operated by a cross bar 5, of properinsulating material. Said bar is fastened to a crank consisting of anarm- 6 connected to a crank proper 7, secured to a crank shaft 8journaled in a bearing 9 bolted or otherwise fastened to the top of thecabinet, as best shown in Fig. 8. A setting arm 12 is pinned orotherwise fastened to said shaft on the top of the bearing in positionto be engaged by a tripping pawl 13, as best shown in Fig. 6. Said pawlis pivoted upon a stud 14 extending downward from a boss 15 formed onthe under side of an operating lever 16. Said lever has a stationaryfulcrum concentric with sh. ft 8, and in the preferred construction thefulcrum consists of an arbor 18 screwed or otherwise fastened to an arm20 formed integral with the bearing casting 9. Said lever is held inposition by a washer 21 and cotter pin 22, or other suitable holdingmeans. Lever 16 is furnished with a handle 23. The construction of theseparts may, however, be

the spirit of the invention.

, strained by movin A strong spring 25 coils around the-boss 26 of thebearing castin 9, and is held fast at one end, for eira-mp e by thescrew 27 screwing into said casting, as best shown in Figs. 2, 4i and 6.The free end of said spring engages and backs up the setting arm 12 insuch manner as to. tend to throw said arm and the shaft 8' andconnectedparts in a clockwise direction, Figs. '3 and 5. This throws theswitch blades from the starting,

to the running contacts on the panel, as will hereinafter more fullyappear. The arrangement of the parts is such that when pawl 13 and thelever on which it is mounted are swung in an anti clockwise direction,

3, said pawl will move the setting arm 12 with it against the force'ofthe spring, but after the setting arm has been released, and the pawlhas passed by it, a movement of the pawl in the opposite or returndirection will produce no eflect upon the said setting arm, the pawlmerely sliding over the end of it by reason of the bevel upon thecooperating ends of the parts in question.- The result is that theoperating handle is incapable of moving the setting arm andswitch-blades toward the runnin contacts, such movement beingproduceabfi; the actuating spring 25 which must first be the switchblades over into engagement with the starting contacts.

Thus the current connections are necessarily made in their proper orderand the apparatus is incapable of misoperation. The importance of thiswill be obvious to those skilled in the art. Furthermore, as everythingbut the operating lever is inclosed, there is no danger from tire, andby locking the door the parts become inaccessible to an unauthorizedperson. Thus, as a result of my construction, the switch may be operatedwithout exposing the parts, and at the same time the switch cannot beoperated im' properly. 1

Thetripping pawl 13 is held to its work in rotating the setting arm 12by trigger mech- I anism consisting of a pin 30 which normally engagessaid pawl, as best shown in Fig. 6, and is retracted by a trigger 31.-Said pin is longitudinally movable in a lu 32 formed on the under sideof lever 16. his pin has a head 33 formed on the side of the boss onposite to pawl 13 and is backed u and held in projected or actingosition y a compression spring 341- whic in turn is backed up by aportion of the lever itself. Between the pin headand the" lug lies aportion of the trigger 31 which is apertured to receive said pin. Thetrigger is thus held in position by the pin and when manipulated by thethumb of the operator, retracts said pin and releases the pawl 13. Saidpawl is yieldingly held in position to engage arm 12 by only by theopposite direction to the end of its throw, I

thus bringing the switch blades into engagement with the startingcontacts. This action strains the actuating spring 25. The attendantholds the parts in this position until the motor has attained thenecessary speed, whereupon he presses his thumb upon the trigger 31which retracts pin 30 and releases the tripping pawl 13. This in turnreleases the setting" arm .12, whereupon spring 25 instantly throws theswitch blades over into engagement with the running contacts. Actingunder the force of the spring the movement of the switch blades is veryquick, and consequently eliminates arcing and burning of the contacts.

lit is desirable that the apparatus be constructed and mounted in suchmanner that the switch blades will swing in a horizontal plane, thuseliminating the effect of gravity in tending to open or close theswitch. This characteristic, however, is not essential, and theactuating spring 25 may be made of proper strength to operate the switchblades moving in any lane.

T will now escribe the arrangement of the contacts and switch bladeswhereby with a single throw of a four pole switch I am able to change athree phase induction motor over from star connecton to deltaconnection: 3

Attached to the cross bar 5, above mentioned, are four switch blades 41,42, 43, A l. These are hinged to and in permanent electric connectionwith the contacts 51, 52, 53 and 54 respectively. Said contacts 51, 52,53 and 5 1 are connected respectively by the conductors 61, 62, 63, andfuses-'71, 72, '73, I, to the three main line conductors which supplythe electrical energy. At the extreme right, in line respectively withthe contacts 51, 52, 53 and 54, are contacts 81, 82, 83 and 84 whichwill be engaged by the switch blades when the latter are in startingposition. A contact 85 is located between the contacts 54: and 84 inline to be engaged by blade at when the latter is in engagement withcontact 84. At the left, in line respectively with the contacts 51, 52,53, are contacts 91, 92, 93 and other contacts 101, 102 and 103. Thecontacts 91, 92 and 93 are respectively connected by conductors 111, 112and 113 to one end of the phase windings 121, 122 and 123. The oppositeends of said windings are respectively connected to conductors 131, 132and133; the con ductor 131 leading to the contacts 85 and -nected bytime.

tacts 54 and 103andthe conductor 133 leading to-the contacts 84 and 101.Contacts 81 and-91 are, connected ,by a conductor 141. Contacts 82 and92 are connected by a conductor 142, and contacts 83 and 93 are conaconductor 143. By referring to the diagram it will be seen that when theswitch blades are thrown to the right, the

motor will be star connected, and that when thrown to the left, themotor will be delta; connected, and the change is thus made bythe aid ofa switch having but four poles or blades and having but two actingpositions.-

Having thus described my invention, what I claim as new, ters Patent,is:

1. In an electric switch the combination with the stationary contactsand a switch blade adapted "to be thrown from one contact to'the other,of an actuating spring for throwing the blade, a setting arm for forcingback the blade against the force of the spring, a tripping pawl andmeans for operating said pawl, said pawl bein adapted to engagesaid armwhenmoved in one direction and to slip over without engaging said armwhen moved in the opposite direction 2. In a motor switch, thecombinationof a starting contact, a running contact, a switch armmovable from one to the other, and quick throw mechanismv comprising a.spring adapted to move the switch arm toward the running contact, ahandle adapted to move the switch arm toward the starting contact, andmeans for quickly releasing said spring, said handle being ineffectiveto move said switch arm towardthe run-' other, a spring adapted to movethe switch arm toward the runnin contact, a rotary setting arm forcontro ling said switch arm, a lever fulcrumed concentrically with saidsetting arm, a. tripping pawl adapted to move said setting arm in adirection to move the switch arm toward the starting contact, saidtripping pawl being non-active upon said setting arm in the oppositedirection, and a trigger mounted on said lever for controlling saidtripping pawl.

4. In a switch, the combination with a movable switch arm, of a settingarm adapted to operate said switch arm, a sprin adapted to move saidswitch arm in one direction, a tripping pawl adapted to move saidsetting arm in the opposite direction only, a trigger pin adapted tohold said tripping pawl to its work in moving the settin arm against theforce of the s ring, an a lever whereon said pawl and pin are and desireto secure by Let- :with the switch.

, panel therein,

running contact on said panel, a switch .-,m0unted,fisaid pawl and pinboth being yielding, and the pawl being adapted to slip over withoutengaging the setting arm, and adapted to force back to non-actingposition the pin when the operating lever moves the pawl and pin in thedirection op osite to the one in which the pawl is capa le of engagingthe setting arm. 1

5. In a motor starting switch, the combi' nation of a starting contact,a running contact, apivoted switch arm adapted to swing from one ;to theother, a spring adapted to swing-theswitch arm toward the runningcontact, az'setting arm concentric with the switch arm, an operatinglever concentric 7 arm and setting arm, a tripping pawl adapted toengage said setting arm to swing the switch arm toward the startingcontact, said tripping pawl being yieldingly mounted and adapted to slipover the setting arm when moved in the opposite direction, a yieldabletrigger pin adapted to engage said pawl to hold it to its work, anda'trigger for retracting said pin to thereby suddenly trip said pawl.

6. In apparatus of the class described, the combination of a cabinet, aninsulating a starting contact and :1

arm mounted on said panel, a spring adapted to move said arm intoengage-- ment with the running contact, a lever mounted on the cabineton the outside thereof, means including a tripping pawl and pin mountedon said lever adapted to connect said lever with said switch arm to movethe latter into engagement with the starting contact, and a trigger oerative upon said pin for disconnecting tlie lever from the switch arm.

7. A three phase induction motor switch comprising a four pole switcharm having' three phase blades permanently connected respectively to thethree phases of the source of electric energy, and a fourth or extrablade normally insulated therefrom, three starting contacts adapted tobe engaged respectively by the three phase blades of the switch arm whenthe latter is in starting position, three running contacts adapted to beengaged respectively by the three phase blades when the switch arm is inrunning position, the starting and running contacts for any phase. bladebeing both connected to the same end of the same phase winding, threeextra contacts connected respectively to the remaining ends of the threephase windings of the motor, said three extra contacts being adapted tobe all engaged by the extra switch blade when the switch arm is instarting position to thereby short circuit the inner ends of the phasewindings of the motor for. throwing the same into star connection, andthree contacts adapted to be engaged respectively by the an um;

three phase blades of the switch arm when the latter is in runningposition to be thereby short circuitedwith the three running contactsabove mentioned to throw the phase windings of the motor into deltaconnection. 1

8. In an electric switch, the combination of a panel, a switch bladehinged thereto and adapted to swing in a plane at right angles to theplane of the board, contacts on said board on opposite sides ofthe'hinge of the switch blade, said blade being adapted to be thrownfrom one contact to the other, an actuating springfor throwing theblade, a setting arm for forcing back the blade against the force of thespring, a hand lever, atripping pawl on said lever adapted to move saidsetting arm in the direction to strain said spring, and triggermechanism on said hand leverfor controlling said tripping pawl.

In witness whereof I have hereunto subscribed my name inpresence of twowitnesses.

OTIS B.'DUNCAN. Witnesses:

HOWARD M. Cox, ETTA L. HITE.

